Poly(trimethylene terephthalate) (also referred to as “3GT” or “PTT”) has recently received much attention as a polymer for use in textiles, flooring, packaging and other end uses.
Certain end uses place rigorous demands on fibers. For example, in automotive interiors, fabrics are expected to maintain desirable physical properties over extended periods of use and, potentially, extreme environmental conditions. Even with the advent of sun-shielding tinted windows, UV exposure can be very high. Compounding this are extremes in temperature ranges spanning from sub-freezing, wherein softness is generally preferred to brittleness, to super heated greenhouse-like conditions, especially in more southern areas of the North American continent. Transportation end uses, from aircraft to pleasure boats, have some of the same rigorous conditions of more widespread automotive end uses.
In the area of automotive interiors, different end uses include seat covering material, door panel decorative panels and headliners. Colorfastness is desired in all of these applications. Maintenance of physical characteristics other than color is also desirable. In some of these applications, perhaps more important than absolute value for any given physical parameter, e.g. elongation, (some of which can be compensated for by design considerations), is the stability of physical performance over extended periods of testing/time.
In addition to transportation linked end uses, outdoor end uses including housing (awnings), garden and patio furniture, and certain items of apparel and personnel (sun) protective equipment can place extreme UV and heat stability requirements on fabric materials employed.
A fabric material possessing highly desirable aesthetic qualities is fabric made with fibers comprising poly(trimethylene terephthalate), also referred to as “PTT” or “3GT”. Such fabrics exhibit softness (hand), resiliency, and stretch recovery, among other desirable properties. Physical properties of testing interest include tenacity and elongation.
Travel and Transportation Textiles (Ciba Specialty Chemicals, Inc., April 2000) presents an overview of automotive fabric dyeing technology. The potential utility of poly(trimethylene terephthalate) fiber in automotive fabrics is discussed in view of its attractive physical properties, but results of high temperature light fastness tests indicate “difficulties in reaching the level of performance of regular polyester” (i.e. polyethylene terephthalate). The publication states that “regular polyester has become and will remain the dominant fiber for upholstery for at least the near future”. The use of UV absorbers is discussed as a method of improving lightfastness, but only in connection with regular polyester (Tersuisse® brand of polyester from Rhodia was used in testing.) JP 2000 192375A discloses a method for dyeing poly(trimethylene terephthalate) fabric to yield sublimation color fastness. The publication discloses that after dyeing the poly(trimethylene terephthalate) fabric at 90–140° C., for 15 to 90 minutes, the dyed fabric is removed from the dyebath at a temperature between 55° C. and the boiling point of the dyebath, which provides the desired colorfastness. The only tests carried out on the resulting dyed poly(trimethylene terephthalate) fabrics are tests for sublimation fastness and sublimation fastness during storage.
JP 2002 180384A discloses a dyed article composed of poly(trimethylene terephthalate) fiber having color fastness to light of grade 3 or higher, and a production method thereof, a triazine and/or benzotriazine derivative as a light resistance improving agent. The publication discloses that dyeing can be carried out at 90–130° C. for 15 to 120 minutes, and exemplifies dyeing at 120° C. for 45 minutes. Conditions of UV exposure and lightfastness testing are not disclosed.
It is known that poly(trimethylene terephthalate) can be dyed at atmospheric pressure, at temperatures of 100° C. or less, in aqueous media. For example, U.S. Pat. No. 5,782,935 discloses a process for the dyeing of poly(trimethylene terephthalate) fibers by treating the fibers in an aqueous liquor in the absence of a carrier and without the application of pressure, at or below the boiling point of the aqueous liquor. U.S. Pat. No. 6,187,900 B1 discloses a dyeable fiber of poly(trimethylene terephthalate) and poly(ethylene terephthalate); dyeing is carried out at or below 100° C. in the absence of a carrier. JP 2002 054047A discloses that the dyeing of sewing thread comprising poly(trimethylene terephthalate) is advantageously carried out at atmospheric pressure at 98° C. rather than under pressure at 120° C.
The ability to dye poly(trimethylene terephthalate) fibers at higher temperatures and pressures than those at which such dyeing is conventionally carried out, and to provide poly(trimethylene terephthalate) having improved colorfastness, are desired. The present invention is directed to these and other important ends.